1. Field of the Invention
The present invention relates to an information terminal device that is capable of transmitting data to and from a server device on a communication line. More specifically the invention pertains to the technique of preventing intentional or unintentional leakage of confidential data from the information terminal device.
2. Background Art
The advancement of the communication technology and the computer-related technology has significantly enhanced the performances of diverse information terminal devices including cell phones, PDAs (personal digital assistances), and laptops. These information terminal devices have the comparable throughput to those of some old versions of desktop computers. With the improved performances, various functions including a mail function, a browser function, a word processing function, and a spreadsheet function are installed in such information terminal devices. These information terminal devices are mobile and portable and are thus usable at any time and at any location, for example, during a business trip or during a travel.
The information terminal device is mobile and portable and is thus not free from the possibility of being lost or stolen to be transferred to the third person. There is accordingly a fear that confidential data stored in the information terminal device is leaked to the outside. In order to enable the information terminal device to safely deal with emails of confidentiality and other confidential data including important document data, one proposed technique sets a password to the confidential emails and the confidential data and requires entry of the valid password to open the confidential emails and the confidential data (see Japanese Patent Laid-Open Gazette No. 2003-209544).
The proposed technique requires entry of the valid password to open the confidential data. The display of a folder for storage of the confidential data and a password entry window, however, undesirably informs the third person of the presence of the confidential data. There is accordingly a fear that the third person breaks the password and leaks the contents of the confidential data to the outside.
The object of the invention is thus to eliminate the drawbacks of the prior art technique and to provide a technique of concealing even the presence of confidential data to any third person and thus enabling an information terminal device to safely and securely deal with the confidential data.